Tug Power

The first tugboats in the Coos Bay area used steam engines, and steam-powered tugs remained in service until the 1950s. Steam offered advantages because wood and coal were abundant and cheap, and the engines were fairly simple, reliable, and powerful. In the early 1900s, internal combustion gasoline and diesel engines began replacing steam because they could start instantly, took less space, and converted fuel to energy more efficiently. The Koos No. 2 used a Cummins V-12 cylinder marine diesel rated at 450 horsepower, enough for the 49-foot vessel to tow log rafts and move sawdust barges. Installed in 1958 as the boat's fourth engine, it had run more than 100,000 hours by the time it was retired in 1987. Smaller harbor tugs may have less than 400 horsepower, while larger oceangoing tugs may have as much as 4000 horsepower, and a marine diesel engine for a tug the size of Koos No. 2 weighs more than most cars.

Coos Bay, Oregon · United States